• The certificate has been revoked. For example, the website owner can request revocation if the site was hacked. 
• The certificate was issued illegally. The certificate must be issued by a certification authority after a proper check. 
• Windows root certificates are not updated. For example, the DST Root CA X3 certificate, on which website certificates in a browser are based, expired on September 30, 2021. To see on which Windows root certificate the website certificate is based, click View certificate in the warning message ang go to the Certification Path tab. For instructions on updating root certificates on Windows 7, 8, 8.1, 10, see below.
• The certificate chain is broken. The certificates are checked in a chain from the self-signed certificate to the trusted root certificate issued by the certification authority. The certificates in between are used for verification of other certificates in the chain.
  Possible causes of the broken certificates chain:
  • The chain consists of one self-signed certificate. Such certificates are not verified by the certification authority and cannot be trustworthy.
  • The chain does not end with a trusted root certificate.
  • The chain contains certificates which are not meant to sign other certificates.
  • The root or intermediate certificate has expired or its operation period has not begun yet. The certification authority issues a certificate for a limited period of time. 
  • The chain cannot be built.
• The domain specified in the certificate does not match the website to which the connection is established.
• The certificate is not meant to confirm the node authenticity. For example, the certificate is intended only for encrypting the connection between the user and the website.
• Certificate usage policy has been violated. The policy of the certificate is a set of rules which defines the use of the certificate with the specific security requirements. Each certificate must correspond to at least one policy. If there are several policies, the certificate must correspond to all of them. 
• Certificate structure is broken.
• An error occurred when checking the certificate signature.

1. In the main window of your Kaspersky application, click .
2. Go to Security settings and click Network settings.
3. Click Trusted addresses → Add. 
4. Specify the website address that was displayed in the certificate warning message. Select the Active status and click Add.
5. Click Save.
6. Click Save → Confirm.

The website will be added to trusted and excluded from scanning.

1. In the main window of your Kaspersky application, click .

2. In the settings window, go to the Network settings section and select Manage exclusions.

3. Click Add. 

4. Specify the website address that was displayed in the certificate warning message. Select the Active status and click Add. 

5. Click Save.

6. Click Save → Yes.

The website will be excluded from the encrypted connections scan scope.

1. Download the CA.zip archive.
2. Extract the files from it to the C:\CA folder. If there is no such folder, create it.
3. Open the command line as an administrator. See this article for instructions.
4. Run the following command:

After running the command, a new line will appear. This means that the update was successful.

5. Restart your computer.

Root certificates will be updated. We also recommend to install all the available updates for Windows and the browser you are using.

If you have already added the website to the list of scan scope exclusions but the certificate warning message keeps reappearing, restart your Kaspersky application or your computer.

If restarting the application doesn't help, contact Kaspersky technical support by choosing the topic and filling out the form.